Glow Plug Protective Tube Plastic Deformation
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Solution Overview
Problem
Ceramic glow pins in existing glow plugs are prone to fractures, and if they break, fragments can enter the engine combustion chamber, posing a risk.
Innovation Solution
The protective tube of the glow plug is widened through plastic deformation to accommodate the contact element and tapered end section of the ceramic glow pin, enhancing mechanical stability and protection while allowing pressure measurements without interference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the protective tube is enlarged by drilling, then the contact element can be accommodated, but the wall thickness decreases and mechanical stability is compromised
Solution Approach 1:
The protective tube undergoes plastic deformation to change its dimensional parameters. Specifically, the tube is radially expanded by applying force through a mandrel or similar tool, increasing the inner diameter to accommodate the contact element while maintaining the original wall thickness. This parameter change resolves the contradiction by allowing dimensional modification without material removal.
Solution Approach 2:
The protective tube is divided into functionally distinct sections: a widened section that accommodates the contact element and a narrower section that maintains structural integrity. This segmentation allows different parts of the same component to serve different functions - one part provides accommodation space while another preserves mechanical strength.
2Reliability
If the protective tube is widened to accommodate the contact element, then the ceramic glow pin is better protected, but the wall thickness decreases reducing protective function
Solution Approach 1:
Plastic deformation is used to change the geometric parameters of the protective tube, specifically increasing the inner diameter while preserving wall thickness. This allows the tube to be widened for better protection of the ceramic glow pin without sacrificing the structural strength needed to maintain its protective function.
3Measurement precision
If the protective tube is widened, then pressure measurement is enabled without interference signals, but the mechanical stability is negatively affected
Solution Approach 1:
The protective tube is radially expanded through plastic deformation to create a widened section that accommodates pressure sensing elements. This parameter change enables pressure measurement functionality while the deformation process is controlled to maintain sufficient wall thickness and radial stability for accurate signal transmission.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces the risk of ceramic glow pin fractures and prevents fragments from entering the combustion chamber, maintaining mechanical stability and effective pressure signal transmission.
Implementation Method 1
an end section of the protective tube is widened, i.e., its inner diameter and its outer diameter are increased, for example by plastic deformation
Data Source
AI summary
Described is a glow plug having a casing and a ceramic glow pin protruding out of the casing. The glow pin has a tapered end section inside the casing. A metal protective tube protrudes out of the casing and surrounds the glow pin. The protective tube has a widened end section inside the casing. A center electrode is arranged in the casing and electrically connected to the glow pin. The glow plug includes an annular or sleeve-shaped contact element through which the glow pin projects and to which the tapered end section of the glow pin is soldered. The contact element is at least partly surrounded by the widened end section of the protective tube.